1. Field of the Invention
The invention relates to a method for preparing catalysts useful in the manufacture of maleic anhydride by the oxidation of aliphatic hydrocarbons, and more particularly to low attrition catalysts suitable for producing maleic anhydride from saturated hydrocarbons in high yields.
2. Description of the Prior Art
Bergman et al., U.S. Pat. No. 3,293,268 (hereby incorporated by reference) teaches a process of oxidizing saturated aliphatic hydrocarbons to produce maleic anhydride under controlled conditions in the presence of a phosphorus-vanadium-oxygen catalyst.
Typical phosphorus-vanadium-oxygen catalysts for use in tube-type reactors are formed as pills, pellets, slugs, tablets, or extrusions, collectively termed "agglomerates". Charging of such catalyst agglomerates to a reactor is a problem because the agglomerates are dusty, that is, have very low breakage and attrition resistance, and the phosphorus-vanadium-oxygen dust is moderately toxic. When catalyst structures are broken the breakage can cause undesirable pressure drop difficulties during reactor operation. In attempts to alleviate such problems, high density forms have been employed using higher tabletting pressures. These high density forms, with corresponding lower porosity, are less active than low density forms.
If the crush strength of low density phosphorus-vanadium-oxygen catalysts could be significantly improved without detriment to catalyst performance such improvement would constitute a significant advance in the art and is an object of this invention.